Methods and compositions for determination of fracture geometry in subterranean formations

ABSTRACT

Disclosed herein is a method comprising disposing in a formation fracture, a proppant and/or a fracturing fluid that comprises a radiation susceptible material that comprises indium and/or vanadium; irradiating the radiation susceptible material with neutrons; measuring gamma-radiation emitted from the radiation susceptible material in a single pass; wherein the single pass does not involve measuring of background radiation from previous or subsequent logging passes; and determining formation fracture height from the measured gamma-radiation.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of co-pending U.S. patentapplication Ser. No. 12/789,094, filed May 27, 2010, which applicationis a divisional application of U.S. patent application Ser. No.11/501,575, filed Aug. 9, 2006, issued as U.S. Pat. No. 7,726,397, whichapplication claims benefit to U.S. Provisional Application No.60/706,791, filed Aug. 9, 2005, of which the entire contents of allapplications are incorporated by reference herein.

FIELD OF THE INVENTION

This disclosure relates to methods and compositions for determiningfracture geometry in subterranean formations.

BACKGROUND

The yield of hydrocarbons, such as gas and petroleum, from subterraneanformations can be increased by fracturing the formation in order tostimulate the flow of these hydrocarbons in the formation. Variousformation fracturing procedures are now used, such as, for example,hydraulic fracturing in which liquids, gases and or combinations of bothare injected into the formation under high pressure (usually withpropping agents).

Hydraulic fracturing is often used in the industry for improving oil andnatural gas production from subterranean formations. During a hydraulicfracturing operation, a fluid, generally termed a “pad”, is pumped downa well at sufficient pressure to fracture open the formation surroundingthe well. Once a fracture has been created, the pumping of the pad,along with a slurry phase that comprises both the liquid and a proppant,is begun until a sufficient volume of the proppant has been carried bythe slurry into the fracture. After a suitable time, the pumpingoperation is stopped at which time the proppant will prop open thefracture in the formation, thereby preventing it from closing. As aresult of the fracture, trapped hydrocarbons are provided a moreconductive pathway to the wellbore than was previously available,thereby increasing the well's production. In addition to creatingdeep-penetrating fractures, the fracturing process is useful inovercoming wellbore damage, to aid in secondary operations and to assistin the injection or disposal of produced formation brine water orindustrial waste material.

During the fracturing process, the fractures propagate throughout theformation. The vertical propagation of these fractures is useful indetermining the extent of fracture coverage as it relates to theproducing interval. Fracture height measurements aid well operators indetermining the success of the fracturing operation and, if necessary,to optimize future treatments, for other wells in the field. Inaddition, fracture height information can aid in the diagnosis ofstimulation problems such as lower production rates or unfavorable watercuts. The fracture height data can indicate whether communication hasbeen established between the producing formation and adjacent water ornon-hydrocarbon producing formation zones. Height measurements alsoprovide a check on the accuracy of fracture design simulators used priorto the job to predict fracture geometry. If excessive fracture heightgrowth is determined this would imply that the fracture length isshorter than the designed value.

As previously stated, one reason for monitoring the vertical propagationof a fracture is the concern for fracturing outside of a definedhydrocarbon-producing zone into an adjacent water-producing zone. Whenthis occurs, water will flow into the hydrocarbon-producing zone and thewellbore, resulting in a well that produces mainly water instead of thedesired hydrocarbon. Furthermore, if there is still the desire tocontinue producing hydrocarbons from the well, operators must solve theserious problem of safely disposing of the undesired water. Addressingthe problems arising from an out of zone fracture will also add expensesto the operations. In addition, if the fracture propagates into anadjacent non-hydrocarbon producing formation, the materials used tomaintain a fracture after the fluid pressure has decreased may be wastedin areas outside the productive formation area. In short, it isexpensive to save a well that has been fractured out of thehydrocarbon-producing zone.

Because of the serious problems that can occur as a result of out ofzone fractures, it is desirable to determine formation fracturedevelopment. There are several techniques and devices used formonitoring and evaluating formation fracture development such asradioactive tracers in the fracturing fluid, temperature logs, boreholeteleviewers, passive acoustics and gamma-ray logging. Most techniquesprovide some direct estimates of fractured zone height at the wellbore.

One process used to determine formation fracture height developmentemploys a radioactive tracer. In this process, a fracturing fluidcontaining a radioactive tracer is injected into the formation to createand extend the fractures. When these radioactive fluid and proppanttracers are used, post fracture gamma-ray logs have shown higher levelsof activity opposite where the tracer was deposited, thereby enablingoperators to estimate the development of the fractures.

Another approach for determining fracture height uses temperature andgamma-ray logs. Temperature logs made before and after stimulation arecompared to define an interval cooled by injection of the fracturingfluid and thus provide an estimate of the fractured zone. However, thistechnique is subject to limitations and ambiguities. For example, thetemperature log may be difficult to interpret because of low temperaturecontrast, flowback from the formation before and after the treatment, orfluid movement behind the borehole casing. In addition, the use ofradioactive tracers gives rise to environmental problems such as thepollution of underground water streams, and the like, and hence isundesirable.

Other methods for evaluating fracture geometry comprise using a boreholeteleviewer or using acoustical methods. Utilizing a borehole televieweris limited in that it can only be used for fracture height evaluation inopen holes. In addition, utilizing a borehole televiewer is limited dueto the extreme temperature and pressure conditions present in deepercompletions. Acoustical methods are hampered by inhomogeneous formationimpedance and/or the need for pumping while the tool is in the hole.

In addition to the problems associated with each type of monitoring,there are inherent problems in the formation fracturing technology.During the fracturing process, fracture fluid is generally pumped intothe formation at high pressure, to force open the fractures, and anincreasing proportion of sand is added to the fluid to prop open theresulting fractures. One problem with the existing technology is thatthe methods for determining whether a formation has been fractured outof the production zone relies on post-treatment (after the fracture hasoccurred) measurements. In such systems, a fracturing treatment isperformed, the treatment is stopped, the well is tested and the data isanalyzed. Moreover, with existing detection systems, the wait forpost-fracturing data can take a considerable amount of time, even up toseveral days, which can delay the completion operations, resulting inhigher personnel and operating costs.

Another problem associated with existing post-process “logging” ormeasuring devices is that the cost associated with interrupting afracturing job in order to make a measurement of a fracture is neitherpractical nor feasible. Because the fracturing fluid is pumped into aformation under high pressures during the fracturing process,temporarily halting the pumping during the fracturing operation willresult in the application of pressure to the fracturing fluid by thewalls of the formation fracture. This could lead to undesirable resultssuch as the closing of the fractures, thereby causing the reversal offluid flow back into the borehole, or the build-up of sand in the hole.In addition, after taking measurements and completing the loggingprocess, operators cannot restart the pumping equipment at the point ofthe fracturing process immediately before the interruption. Instead, theoperators would have to repeat the complete fracturing job at additionalcost and with unpredictable results.

A monitoring system could address the above-described problems and wouldallow well operators to monitor the fracturing process, to controlfracture dimensions and to efficiently place higher concentrations ofproppants in a desired formation location. In addition, if there isinformation that a fracture is close to extending outside the desiredzone, operators can terminate the fracturing job immediately.Furthermore, analysis of the ongoing treatment procedure will enable anoperator to determine when it is necessary to pump greaterconcentrations of the proppant, depending on factors such as thevertical and lateral proximity of oil/water contacts with respect to thewellbore, the presence or absence of water-producing formations andhorizontal changes in the physical properties of the reservoir rock.

It is therefore advantageous to monitor fracture geometry using methodsand compositions that are inexpensive, predictable and environmentallyfriendly.

SUMMARY

Disclosed herein is a method comprising disposing in a formationfracture, a proppant and/or a fracturing fluid that comprises aradiation susceptible material; and during a single logging passirradiating the radiation susceptible material with neutrons; measuringgamma-radiation emitted from the radiation susceptible material;subtracting background radiation from peak energy radiation emanatingfrom the indium and/or vanadium; and determining formation fractureheight from the measured gamma-radiation.

Disclosed herein too is a proppant comprising a substrate; a coatingdisposed upon the substrate; wherein the substrate and/or the coatingcomprises a radiation susceptible material that comprises indium and/orvanadium.

Disclosed herein too is a proppant comprising a composite substratecomprising an organic or inorganic material; a filler dispersed therein;and a radiation susceptible material comprising vanadium and/or indium.

DETAILED DESCRIPTION OF FIGURES

FIG. 1 depicts one exemplary embodiment of a proppant comprising a solidcore upon which is disposed an organic coating that comprises theradiation susceptible material;

FIG. 2 depicts another exemplary embodiment of a proppant comprising acore made up of particulates upon which is disposed an organic coatingthat comprises the radiation susceptible material; and

FIG. 3 depicts another exemplary embodiment of a proppant that comprisesan organic material in which is dispersed a filler and the radiationsusceptible material.

DETAILED DESCRIPTION

It is to be noted that as used herein, the terms “first,” “second,” andthe like do not denote any order or importance, but rather are used todistinguish one element from another, and the terms “the”, “a” and “an”do not denote a limitation of quantity, but rather denote the presenceof at least one of the referenced item. Furthermore, all rangesdisclosed herein are inclusive of the endpoints and independentlycombinable.

Disclosed herein is a method for determining fracture geometry that usesenvironmentally friendly materials. These environmentally friendlymaterials are non-radioactive until bombarded by neutrons and will bereferred to as radiation susceptible materials. In one embodiment, themethod involves determining fracture geometry of a formation usingtarget elements that comprise the radiation susceptible materials. Theradiation susceptible materials have a short half-life, whichadvantageously permits them to be used in a formation while at the sametime minimizing any adverse environmental impact, either from handlingor having the proppant flow back out of the well after the well is putback on production.

As noted above, radiation susceptible materials as defined herein arethose that become radioactive upon bombardment by neutrons. Theradiation susceptible materials can advantageously be disposed in thefracturing fluid, or in a coating disposed upon a proppant that isdisposed in the fracturing fluid or as a part of core of the proppantitself. The fracturing fluid or the proppant that comprises theradiation susceptible material can be used during a hydraulic fracturingtreatment. The fracturing fluid and/or the proppants that comprise theradiation susceptible materials are injected into the fracture duringthe creation of the fracture. After being injected into the fracture,the radiation susceptible materials are irradiated with neutrons from aneutron source. Gamma radiation emitted from the radiation susceptiblematerials is detected by a logging tool. Since the radiation susceptiblematerials have a short half-life, these materials become radioactive foronly a brief period of time. The location of the gamma radiation is usedto determine the placement of the radiation susceptible materials in thefracture and is also used to determine the fracture geometry. In oneembodiment, the location of the radiation susceptible materials isadvantageously used to determine the fracture height.

The present method is advantageous in that background radiation acquiredduring the activation of the radiation susceptible materials can becollected in a single pass and subtracted from the peak energyradiation. All other commercially available processes generally use twoor more logging passes to determine the fracture geometry of thefractured formation. The acquired background radiation generallycomprises multiple contributions from a number of sources. A firstcontribution can generally be acquired from naturally occurringradioactive elements such as uranium, potassium, and/or thorium. Overtime, fine-grained formations can trap minerals and fluids containingthese naturally radioactive elements. When the radiation susceptiblematerials in the formation are activated by neutrons, these naturallyoccurring radioactive materials will also emit radiation, which isacquired as background radiation.

A second contribution to the background is acquired from radioactivetracers that were previously placed in the formation in order todetermine fracture height. This second contribution is therefore derivedfrom radioactive tracers that were placed in the formation in previousattempts that were made to determine the fracture geometry. A thirdcontribution to the background is that induced by neutron radiationbeing presently used to activate the radiation susceptible materials.This radiation emanates mainly from aluminum and silicon present in theformation and/or the proppant. Background radiation from iron/manganeseused in the wellbore casing may also be a part of this thirdcontribution.

It is desirable to remove all traces of background radiation from thepeak energy radiation prior to calculation of fracture geometry. In oneembodiment, the peak energy radiation measurements as well as backgroundradiation measurements are made in a single pass the backgroundradiation measurements are subtracted from the peak energy radiationmeasurements in a single pass.

As noted above, the radiation susceptible materials can be disposed in aproppant that is introduced into the fracture to prop open the fracture.In one embodiment, the proppant can comprise a substrate upon which isdisposed a coating comprising the radiation susceptible material. Inanother embodiment, the substrate can comprise the radiation susceptiblematerial. When a proppant and/or fracturing fluid comprises a radiationsusceptible material, it is said to be tagged with the radiationsusceptible material. The term “tagging” as used herein implies that theproppant and/or the fracturing fluid comprises radiation susceptiblematerials. Thus, when a coating disposed on a substrate comprisesradiation susceptible materials, the proppant is said to be tagged witha radiation susceptible material. The tagging of the proppants and/orthe fluid with a radiation susceptible material permits photo-peak tophoto-peak ratios to be generated upon activation of the radiationsusceptible material. The photo-peak to photo-peak ratios providemeasurements of the vertical height of a proppant filled fracture.

With reference now to FIG. 1 or FIG. 2, one exemplary embodiment of aproppant 10 comprises a substrate 2 upon which is disposed a coating 4that comprises the radiation susceptible material 6. The coating 4 cancomprise an organic or an inorganic material. The substrate 2 cancomprise an organic material and/or an inorganic material and/or ametal. The coating 4 can be uncured, partially cured or fully curedprior to use in a subterranean fracture. This curing can occur eitherinside and/or outside the subterranean fracture.

The coating 4 can optionally comprise particulate fillers or fibrousfillers 8 if desired. The proppant 10 of FIGS. 1 and 2 comprises ametallic and/or inorganic substrate 2 that generally comprises a singleparticle or is an agglomerate comprising a plurality of particles.Examples of metals that can be used in the substrates are shape memoryalloys. Shape memory alloys exhibit a “shape memory effect”. The shapememory effect permits a reversible transformation between twocrystalline states i.e., a martensitic state to an austenitic state andvice versa. Generally, in the low temperature, or martensitic state,shape memory alloys can be plastically deformed and upon exposure tosome higher temperature will transform to an austenitic state, therebyreturning to their shape prior to the deformation.

A suitable example of a shape memory alloy is a nickel titanium alloysuch as NITINOL®. It is desirable for the shape memory alloys to befoamed. In one embodiment, a substrate manufactured from a shape memoryalloy can be a solid prior to introduction into the fracture, but canexpand into a foam after introduction into the fracture, which isgenerally at a higher temperature than the temperature above ground.This expansion will permit better conductivity of oil and gas from thefracture.

Examples of inorganic materials that can be used in the substrate areinorganic oxides, inorganic carbides, inorganic nitrides, inorganichydroxides, inorganic oxides having hydroxide coatings, inorganiccarbonitrides, inorganic oxynitrides, inorganic borides, inorganicborocarbides, or the like, or a combination comprising at least one ofthe foregoing inorganic materials. Examples of suitable inorganicmaterials are metal oxides, metal carbides, metal nitrides, metalhydroxides, metal oxides having hydroxide coatings, metal carbonitrides,metal oxynitrides, metal borides, metal borocarbides, or the like, or acombination comprising at least one of the foregoing inorganicmaterials. Metals used in the foregoing inorganic materials can betransition metals, alkali metals, alkaline earth metals, rare earthmetals, or the like, or a combination comprising at least one of theforegoing metals.

Examples of suitable inorganic oxides that are synthetically producedinclude silica (SiO₂), alumina (Al₂O₃), titania (TiO₂), zirconia (ZrO₂),ceria (CeO₂), manganese oxide (MnO₂), zinc oxide (ZnO), iron oxides(e.g., FeO, a-Fe₂O₃, γ-Fe₂O₃, Fe₃O₄, or the like), calcium oxide (CaO),manganese dioxide (MnO₂ and Mn₃O₄), or combinations comprising at leastone of the foregoing inorganic oxides. Examples of suitablesynthetically produced inorganic carbides include silicon carbide (SiC),titanium carbide (TiC), tantalum carbide (TaC), tungsten carbide (WC),hafnium carbide (HfC), or the like, or a combination comprising at leastone of the foregoing carbides. Examples of suitable syntheticallyproduced nitrides include silicon nitrides (Si₃N₄), titanium nitride(TiN), or the like, or a combination comprising at least one of theforegoing. Exemplary inorganic substrates are those that comprisenaturally occurring or synthetically prepared silica and/or alumina.

Examples of suitable naturally occurring inorganic materials that can beused in the substrate are silica (sand), aeschynite (rare earth yttriumtitanium niobium oxide hydroxide), anatase (titanium oxide), bindheimite(lead antimony oxide hydroxide), bixbyite (manganese iron oxide),brookite (titanium oxide), chrysoberyl (beryllium aluminum oxide),columbite (iron manganese niobium tantalum oxide), corundum (aluminumoxide), cuprite (copper oxide), euxenite (rare earth yttrium niobiumtantalum titanium oxide), fergusonite (rare earth iron titanium oxide),hausmannite (manganese oxide), hematite (iron oxide), ilmenite (irontitanium oxide), perovskite (calcium titanium oxide), periclase(magnesium oxide), polycrase (rare earth yttrium titanium niobiumtantalum oxide), pseudobrookite (iron titanium oxide), members of thepyrochlore group such as, for example, betafite (rare earths calciumsodium uranium titanium niobium tantalum oxide hydroxide), microlite(calcium sodium tantalum oxide hydroxide fluoride), pyrochlore (sodiumcalcium niobium oxide hydroxide fluoride), or the like, or a combinationcomprising at least one of the foregoing pyrochlore group members;ramsdellite (manganese oxide), romanechite (hydrated barium manganeseoxide), members of the rutile group, such as, for example, cassiterite(tin oxide), plattnerite (lead oxide), pyrolusite (manganese oxide),rutile (titanium oxide), stishovite (silicon oxide), or the like, or acombination comprising at least one of the foregoing rutile groupmembers; samarskite-(Y) (rare earth yttrium iron titanium oxide),senarmontite (antimony oxide), members of the spinel group such aschromite (iron chromium oxide), franklinite (zinc manganese iron oxide),gahnite (zinc aluminum oxide), magnesiochromite (magnesium chromiumoxide), magnetite (iron oxide), and spinel (magnesium aluminum oxide),or the like, or a combination comprising at least one of the foregoingspinel group members; taaffeite (beryllium magnesium aluminum oxide),tantalite (iron manganese tantalum niobium oxide), tapiolite (ironmanganese tantalum niobium oxide), uraninite (uranium oxide),valentinite (antimony oxide), zincite (zinc manganese oxide),hydroxides, such as, for example, brucite (magnesium hydroxide),gibbsite (aluminum hydroxide), goethite (iron oxide hydroxide), limonite(hydrated iron oxide hydroxide), manganite (manganese oxide hydroxide),psilomelane (barium manganese oxide hydroxide), romeite (calcium sodiumiron manganese antimony titanium oxide hydroxide), stetefeldtite (silverantimony oxide hydroxide), stibiconite (antimony oxide hydroxide), orthe like, or a combination comprising at least one of the foregoingnaturally occurring inorganic materials.

Naturally occurring organic and inorganic materials that aresubsequently modified can also be used as the substrate. Suitableexamples of organic and inorganic materials that are modified and usedin the substrate are exfoliated clays (e.g., expanded vermiculite),exfoliated graphite, blown glass or silica, hollow glass spheres, foamedglass spheres, cenospheres, foamed slag, sintered bauxite, sinteredalumina, or the like, or a combination comprising one of the foregoingorganic and inorganic materials. Exemplary inorganic substrates may bederived from sand, milled glass beads, sintered bauxite, sinteredalumina, naturally occurring mineral fibers, such as zircon and mullite,or the like, or a combination comprising one of the naturally occurringinorganic substrates. Hollow glass spheres can be commercially obtainedfrom Diversified Industries Ltd.

The organic materials that are used in the substrate can bethermoplastic polymers, thermosetting polymers, or a combinationcomprising a thermosetting polymer and a thermoplastic polymer. Examplesof suitable organic materials that can be used as the substrate arepolymer precursors (e.g., low molecular weight species such as monomers,dimers, trimers, or the like), oligomers, polymers, copolymers such asblock copolymers, star block copolymers, terpolymers, random copolymers,alternating copolymers, graft copolymers, or the like; dendrimers,ionomers, or the like, or a combination comprising at least one of theforegoing. When the substrate comprises a thermosetting polymer, it isdesirable for the organic materials to undergo curing (crosslinking)upon the application of either thermal energy, electromagneticradiation, or a combination comprising at least one of the foregoing.Initiators may be used to induce the curing. Other additives thatpromote or control curing such as accelerators, inhibitors, or the like,can also be used.

Examples of suitable thermosetting polymers for use in the substrate areepoxies, acrylate resins, methacrylate resins, phenol-formaldehydes,epoxy-modified novolacs, furans, urea-aldehydes, melamine-aldehydes,polyester resins, alkyd resins, phenol formaldehyde novolacs, phenolformaldehyde resoles, phenol-aldehydes, resole and novolac resins, epoxymodified phenolics, polyacetals, polysiloxanes, polyurethanes, or thelike, or a combination comprising at least one of the foregoingthermosetting polymers.

Epoxy-modified novolacs are disclosed by U.S. Pat. No. 4,923,714 to Gibbet al. incorporated herein by reference. The phenolic portion cancomprise a phenolic novolac polymer; a phenolic resole polymer; acombination of a phenolic novolac polymer and a phenolic resole polymer;a cured combination of phenolic/furan or a furan resin to form aprecured resin (as disclosed by U.S. Pat. No. 4,694,905 to Armbrusterincorporated herein by reference); or a curable furan/phenolic resinsystem curable in the presence of a strong acid to form a curable resin(as disclosed by U.S. Pat. No. 4,785,884 to Armbruster). The phenolicsof the above-mentioned novolac or resole polymers may be phenol moietiesor bis-phenol moieties.

The thermosets can be cold setting resins. Cold setting resins are thosethat can react at room temperature without the use of additional heat.Cold set resins generally cure at a temperature less than 65° C. Thus,for example, a thermosets that cures at 80° C., is not a cold settingresins. Examples of suitable cold setting resins include epoxies curedwith an amine when used alone or with a polyurethane, polyurethanes,alkaline modified resoles set by esters (e.g., ALPHASET® and BETASET®),furans, e.g., furfuryl alcohol-formaldehyde, urea-formaldehyde, and freemethylol-containing melamines set with acid. For the purposes of thisdescription, a cold set resin is any resin that can normally be cured atroom temperature. ALPHASET® and BETASET® resins are ester curedphenolics.

Urethanes are disclosed by U.S. Pat. No. 5,733,952 to Geoffrey. Melamineresins are disclosed by U.S. Pat. Nos. 5,952,440, 5,916,966, and5,296,584 to Walisser. ALPHASET resins are disclosed by U.S. Pat. Nos.4,426,467 and Re. 32,812 (which is a reissue of U.S. Pat. No. 4,474,904)all of which are incorporated herein by reference.

Modified resoles are disclosed by U.S. Pat. No. 5,218,038, incorporatedherein by reference in its entirety. Such modified resoles are preparedby reacting aldehyde with a blend of unsubstituted phenol and at leastone phenolic material selected from the group consisting of arylphenol,alkylphenol, alkoxyphenol, and aryloxyphenol. Modified resoles includealkoxy modified resoles. An exemplary alkoxy modified resole is amethoxy modified resoles. An exemplary phenolic resole is the modifiedorthobenzylic ether-containing resole prepared by the reaction of aphenol and an aldehyde in the presence of an aliphatic hydroxy compoundcontaining two or more hydroxy groups per molecule. In one exemplarymodification of the process, the reaction is also carried out in thepresence of a monohydric alcohol.

Examples of suitable thermoplastic polymers that can be used in thesubstrate are polyolefins, polyacrylics, polycarbonates, polyalkyds,polystyrenes, polyesters, polyamides, polyaramides, polyamideimides,polyarylates, polyarylsulfones, polyethersulfones, polyphenylenesulfides, polysulfones, polyimides, polyetherimides,polytetrafluoroethylenes, polyetherketones, polyether etherketones,polyether ketone ketones, polybenzoxazoles, polyoxadiazoles,polybenzothiazinophenothiazines, polybenzothiazoles,polypyrazinoquinoxalines, polypyromellitimides, polyquinoxalines,polybenzimidazoles, polyoxindoles, polyoxoisoindolines,polydioxoisoindolines, polytriazines, polypyridazines, polypiperazines,polypyridines, polypiperidines, polytriazoles, polypyrazoles,polycarboranes, polyoxabicyclononanes, polydibenzofurans,polyphthalides, polyacetals, polyanhydrides, polyvinyl ethers, polyvinylthioethers, polyvinyl alcohols, polyvinyl ketones, polyvinyl halides,polyvinyl nitriles, polyvinyl esters, polysulfonates, polysulfides,polythioesters, polysulfones, polysulfonamides, polyureas,polyphosphazenes, polysilazanes, polysiloxanes, phenolics, epoxies, orcombinations comprising at least one of the foregoing thermoplasticmaterials.

Naturally occurring organic substrates are ground or crushed nut shells,ground or crushed seed shells, ground or crushed fruit pits, processedwood, ground or crushed animal bones, or the like, or a combinationcomprising at least one of the naturally occurring organic substrates.Examples of suitable ground or crushed shells are shells of nuts such aswalnut, pecan, almond, ivory nut, brazil nut, ground nut (peanuts), pinenut, cashew nut, sunflower seed, Filbert nuts (hazel nuts), macadamianuts, soy nuts, pistachio nuts, pumpkin seed, or the like, or acombination comprising at least one of the foregoing nuts. Examples ofsuitable ground or crushed seed shells (including fruit pits) are seedsof fruits such as plum, peach, cherry, apricot, olive, mango, jackfruit,guava, custard apples, pomegranates, watermelon, ground or crushed seedshells of other plants such as maize (e.g., corn cobs or corn kernels),wheat, rice, jowar, or the like, or a combination comprising one of theforegoing processed wood materials such as, for example, those derivedfrom woods such as oak, hickory, walnut, poplar, mahogany, includingsuch woods that have been processed by grinding, chipping, or other formof particalization. An exemplary naturally occurring substrate is aground olive pit.

The substrates can have any desired shape such as spherical,ellipsoidal, cubical, polygonal, or the like. It is generally desirablefor the substrates to be spherical in shape. The substrates can haveaverage particle sizes of about 100 micrometers to about 1200micrometers. In one embodiment, the substrates can have average particlesizes of about 300 micrometers to about 600 micrometers. In anotherembodiment, the substrates can have average particle sizes of about 400micrometers to about 500 micrometers.

When a substrate is a porous substrate, it is envisioned that thesubstrate can comprise particles that are agglomerated to form theparticulate substrate. In such a case, the individual particles thatcombine to form the substrate can have average particle sizes of about 2to about 30 micrometers. In one embodiment, the particles thatagglomerate to form the substrate may have average particle sizes ofless than or equal to about 28 micrometers. In another embodiment, theparticles that agglomerate to form the substrate may have averageparticle sizes of less than or equal to about 25 micrometers. In yetanother embodiment, the particles that agglomerate to form the substratemay have average particle sizes of less than or equal to about 20micrometers. In yet another embodiment, the particles that agglomerateto form the substrate may have average particle sizes of less than orequal to about 15 micrometers. Bimodal or higher particle. sizedistributions may be used. Exemplary substrates are spherical in shape.

Porous substrates generally have high surface areas. If the substrate isporous, it is desirable for the substrate to have a surface area ofgreater than or equal to about 10 square meters per gram (m²/gm). In oneembodiment, it is desirable for the substrate to have a surface area ofgreater than or equal to about 100 m²/gm. In another embodiment, it isdesirable for the substrate to have a surface area of greater than orequal to about 300 m²/gm. In yet another embodiment, it is desirable forthe substrate to have a surface area of greater than or equal to about500 m²/gm. In yet another embodiment, it is desirable for the substrateto have a surface area of greater than or equal to about 800 m²/gm.

The density of the substrate can be chosen depending upon theapplication for which the proppant is being used. It is desirable tochoose substrates that can impart to the proppant an apparent density of0.5 to 4 grams per cubic centimeter (g/cc). The apparent density isdefined as the density of the entire proppant (i.e., the weight per unitvolume of the entire material including voids inherent in the proppant).

As noted above, in FIGS. 1 and 2, the substrate has disposed upon it acoating. The coating can be an organic coating, an inorganic coating, ora coating comprising at least one of the foregoing coatings andcomprises the radiation susceptible material. Exemplary organic coatingscan be derived from the thermoplastic and thermosetting polymers listedabove.

The radiation susceptible material that is included in the coating onthe substrate or in the substrate of the proppant is neutron-responsiveso that it readily reacts to neutrons, such as by absorbing thermalneutrons to exhibit a relatively large atomic cross section. By suchresponsiveness to neutrons, the radiation susceptible material yieldsthe characteristic gamma radiation or neutron absorption, which isdistinguishable from the characteristics of the materials in thesurrounding formation. These radiation susceptible materials are alsoinitially non-radioactive so that they can be safely handled withoutfear or risk of radiation exposure or contamination at the surface ofthe well until after it is introduced into the system by which it is tobe moved into the well.

Although the radiation susceptible material is initiallynon-radioactive, the isotope of the radiation susceptible material isone which either becomes radioactive, whereby the created radioactiveisotope decays and emits gamma radiation detectable by a suitabledetector, or otherwise undergoes a nuclear or atomic reaction, such asby simply absorbing one or more neutrons to an extent greater than thematerials of the surrounding formation. Such a reaction can occur inresponse to the external neutrons emitted from an accelerator. If theoriginal substance is to react by forming a radioactive isotope, theradioactive isotope preferably has a known half-life of betweenapproximately a few seconds and up to about 30 minutes so that prolongedirradiation by the accelerator is not needed for the reaction to occurand so that adequate detection time exists once the conversion hasoccurred. It is advantageous that the susceptible material decays to anon radioactive state shortly after the logging process is completed,thereby allowing the well to be brought back into production withoutfear of producing radioactive material.

In one embodiment, the radiation susceptible materials have a half-lifeof about 5 seconds to less than or equal to about 100 days. In anotherembodiment, the radiation susceptible materials have a half-life ofabout 10 seconds to less than or equal to about 50 minutes. In yetanother embodiment, the radiation susceptible materials have a half-lifeof about 12 seconds to less than or equal to about 7 minutes. Anexemplary half-life for a radiation susceptible material is less than orequal to about 5 minutes. Vanadium has a half-life of 3.8 minutes, whileindium has a half-life of 14.1 seconds. It is generally desirable forthe period of measurable radiation to be of a length so that thematerial no longer emits radiation when the well starts producinghydrocarbons. In general, it is desirable for the radiation susceptiblematerial to stop emitting measurable radiation before it is placed backon production. It is also advantageous in that after the half-life ofthe radiation susceptible material has expired, the well can bere-logged as many times as desired by re-irradiating the radiationsusceptible material.

As noted above, the radiation susceptible materials can comprisevanadium and/or indium or combinations comprising at least one of theforegoing radiation susceptible materials. The radiation susceptiblematerials may comprise vanadium and/or indium in all available forms.These forms may include metals, alloys, salts, composites, suspensions,or the like. Vanadium and indium are useful because they have verystrong responses in their natural states. In one embodiment, thevanadium and/or indium metal particles are dispersed in the organicand/or inorganic material prior to coating the substrate. In anotherembodiment, salts of vanadium and/or indium can be dispersed in theorganic and/or inorganic material prior to coating the substrate.

Exemplary vanadium salts that can be used as radiation susceptiblematerials are vanadyl sulfate, sodium or potassium orthovanadate, sodiumor potassium metavanadate, chloride salts of vanadium, or the like, or acombination comprising at least one of the foregoing vanadium salts.Other compounds comprising vanadium can also be used. Examples ofvanadium compounds that can be used are vanadium oxides, such as, forexample, vanadium trioxide, vanadium pentoxide, or the like, or acombination comprising at least one of the foregoing oxides. Otherexamples of vanadium compounds, which can be used alone or incombination with each other, include vanadium metal, vanadium alloyssuch as vanadium/aluminum alloys, ferrovanadium, or a vanadium carbonnitride powder such as NITROVAN vanadium, which is commerciallyavailable from Stratcor, Inc., Pittsburgh Pa.

Exemplary indium salts are indium chloride, indium sulfate, or the like,or a combination comprising at least one of the foregoing indium salts.In one embodiment, salts of indium or vanadium can be dispersed in theproppant coating and can be reacted to form a metal after the proppantis introduced into the formation.

When radiation susceptible materials such as vanadium and/or indiumsalts and/or compounds are used in the coatings, they are used inamounts of up to about 55 wt %, based on the total weight of theproppant. In one embodiment, the radiation susceptible materials areused in amounts of up to about 25 wt %, based on the total weight of theproppant. In another embodiment, the radiation susceptible materials areused in amounts of up to about 15 wt %, based on the total weight of theproppant. In yet another embodiment, the radiation susceptible materialscan be used in amounts of up to 5 wt %, based on the weight of theproppant. The radiation susceptible materials can be used in amounts ofas low as 0.01 wt %, based on the total weight of the proppant.

In another embodiment, when radiation susceptible materials such asvanadium metal, salts and/or compounds are utilized in the proppantand/or the fracturing fluid, they are used in amounts up to about 0.3 wt% as vanadium metal, preferably 0.01 to 5 wt %, preferably 0.05 to 2 wt% and more preferably 0.1 to 1 wt %, based on the total weight of theproppant. In a preferred embodiment, the vanadium compound is a vanadiumcarbon nitride powder or NITROVAN vanadium, having a particle size ofabout 1-15 microns, preferably 1 to 10 microns and more preferably 2-5microns. In another preferred embodiment, the vanadium compound is avanadium carbon nitride powder or NITROVAN vanadium, of 0.01 to 5 wt %as vanadium metal, preferably 0.05 to 2 wt % and more preferably 0.1 to1 wt %, based on the total weight of the proppant.

In addition to vanadium and/or indium, other radiation susceptiblematerials may also be added to the coating. Examples of suitableradiation susceptible materials that may be added to the proppant and/orthe fracturing fluid in addition to the vanadium and/or the indium caninclude iridium 191, iridium 193, cadmium 113, dysprosium, europium,lutetium, manganese, gold, holmium, rhenium, samarium, tungsten, or thelike, or a combination comprising at least one of the foregoingmaterials.

In one embodiment as depicted in FIG. 3, the substrate can comprise acomposite of inorganic and organic materials. Such a substrate is termeda composite substrate. The composite substrate can comprise acombination of inorganic and organic materials. The organic materialscan also be chemically bonded to the inorganic materials. Chemicalbonding comprises covalent bonding, hydrogen bonding, ionic bonding, orthe like. An example of a suitable reaction between an organic and aninorganic material that involves covalent bonding is a sol-gel reaction.The chemical bonding between the organic and inorganic materials canresult in substrates that are nanocomposites. Composite substrates canbe optionally coated with the organic coatings and/or the inorganiccoatings described above.

In one embodiment, the composite substrate can also comprise radiationsusceptible materials. In another embodiment, the radiation susceptiblematerial is introduced during the manufacture of the substrate, inparticular, in the manufacture of a ceramic substrate. In anotherembodiment, when the composite substrate is coated with an organiccoating and/or an inorganic coating, both the composite substrate andthe coating disposed thereon can comprise radiation susceptiblematerials.

The composite substrate can comprise radiation susceptible materials inan amount of up to about 35 wt %, based on the total weight of theproppant. An exemplary amount of the radiation susceptible materials isabout 5 wt %, based on the total weight of the proppant.

In one embodiment, proppants comprising the radiation susceptiblematerial can be mixed with proppants that are free from any radiationsusceptible material prior to introduction into the fracture. Themixture of proppants comprising the radiation susceptible material withproppants that are free from any radiation susceptible material istermed a “proppant composition”. A proppant composition generally willcontain radiation susceptible materials in an amount of up to 55 wt %,based on the total weight of the proppant composition. An exemplaryamount of radiation susceptible materials in the proppant composition isabout 5 to about 10 wt % and preferably about 0.01 to about 5 wt %,based on the total weight of the proppant composition.

In another embodiment, proppants comprising different radiationsusceptible materials can be mixed. For example, a first proppant cancomprise a first radiation susceptible material, while a second proppantcan comprise a second radiation susceptible material. For example, thefirst proppant can include a certain vanadium containing compound, whilethe second proppant includes a different vanadium containing compound oran indium containing compound.

As noted above, the substrate can be solid (i.e., without anysubstantial porosity) or porous if desired. In general, a poroussubstrate permits for impregnation by an organic material, therebyimparting to the substrate an ability to flex and to absorb shock andstress without deforming. The ability of a polymer to impregnate thesubstrate also minimizes the ability of the proppant to fracture,thereby reducing dust generation. By impregnating a porous inorganicsubstrate with an organic material, the density of the proppant can beadjusted to suit various fracture conditions. In general, the substratecan have a porosity of greater than or equal to about 20%, based on thetotal volume of the substrate. In one embodiment, the substrate can havea porosity of greater than or equal to about 50%, based on the totalvolume of the substrate. In another embodiment, the substrate can have aporosity of greater than or equal to about 70%, based on the totalvolume of the substrate. In yet another embodiment, the substrate canhave a porosity of greater than or equal to about 90%, based on thetotal volume of the substrate.

The substrates can be present in the proppants in an amount of about 10to about 90 weight percent (wt %), based on the total weight of theproppants. In one embodiment, the substrates are present in an amount ofabout 20 to about 80 wt %, based on the total weight of the proppants.In another embodiment, the substrates are present in the reactivesolution in an amount of about 30 to about 75 wt %, based on the totalweight of the proppants. In yet another embodiment, the substrates arepresent in an amount of about 35 to about 65 wt %, based on the totalweight of the proppants.

In another embodiment, the radiation susceptible materials can bepresent in the fracturing fluid but not in the proppants. When theradiation susceptible material is present in the fracturing fluid, itcan be present in the form of suspended colloidal particles or it can bedissolved in the fracturing fluid. The fracturing fluid can compriseradiation susceptible materials in an amount of about 0.01 wt % to about35 wt %, based on the total weight of the fracturing fluid. In oneembodiment, the fracturing fluid can comprise radiation susceptiblematerials in an amount of about 2 wt % to about 25 wt %, based on thetotal weight of the fracturing fluid. In yet another embodiment, thefracturing fluid can comprise radiation susceptible materials in anamount of about 3 wt % to about 15 wt %, based on the total weight ofthe fracturing fluid. An exemplary amount of the radiation susceptiblematerials is about 5 wt %, based on the total weight of the fracturingfluid.

In yet another embodiment, both the fracturing fluid and the proppantscontained in the fracturing fluid can comprise the radiation susceptiblematerials. In one embodiment, the fracturing fluid and the proppants canboth contain the same cations. For example, the fracturing fluid cancomprise dissolved vanadyl sulfate, while the proppants contained in thefracturing fluid can comprise vanadium trioxide. Upon being subjected toneutrons, both the vanadyl sulfate and the vanadium trioxide can emitgamma radiation that can be used to calculate the fracture geometry.

In yet another embodiment, the fracturing fluid and the proppantscontained in the fracturing fluid can comprise different cations. Forexample, the fracturing fluid can comprise a first radiation susceptiblematerial, while the proppants contained in the fracturing fluid cancomprise a second radiation susceptible material. For example, thefracturing fluid can comprise vanadyl sulfate, while the proppants cancomprise a salt of indium. In a related embodiment, the fracturing fluidcan comprise a salt of a radiation susceptible material, while theproppant can comprise a radiation susceptible material that comprisesmetal particles. For example, the fracturing fluid can comprise vanadylsulfate while the proppant can comprise particles of indium.

A suitable spectral gamma-ray tool or sonde may be utilized to measurethe gamma radiation obtained from the radiation susceptible materialafter it is bombarded by neutrons. At least a portion of the tool, e.g.,at least the gamma-ray detector, is placed within the well to providethe desired log. The tool can be such as to generate the desired ratiosdownhole, or the gamma-ray spectra can be transmitted to the surface andthe ratios determined from the spectral data. Either a low resolution,e.g., NaI(Tl) or equivalent, detector or a high resolution, e.g.,intrinsic germanium, Ge(Li) or equivalent detector can be used. Since itis desirable to obtain a precise measurement of the peak area or areas ahigh-resolution instrument is generally used. Logs can be generatedeither in a continuous, moving tool mode, or in a stationary mode inwhich the tool is stopped at selected locations in the borehole.

A collimator can be used on the detector if desired. In one embodiment,a rotating collimator is used to measure fracture orientation. Suchcollimators tend to increase the sensitivity of the measurement sincesuch devices reduce the number of gamma rays entering the detector fromlocations up or down the borehole, i.e., gamma rays from proppant thatis behind the casing but is above or below the current location of thedetector. In one embodiment, a detector without a collimator can beused.

In one embodiment, in one method of determining fracture height, taggedproppants and/or a tagged fracturing fluid are introduced into theformation. The tagged proppants and/or tagged fracturing fluid generallycomprise indium and/or vanadium. The tagged proppant and/or taggedfracturing fluid is then bombarded with neutrons during a logging pass.A logging pass is one wherein the logging tool is introduced into thewell and wherein a neutron bombardment of the formation fracture isinitiated. Gamma ray spectroscopy is then performed on the irradiatedindium and vanadium to obtain gamma count rates both above and below thepeak energies (also referred to as off-peak energies) coining fromvanadium and/or indium. Gamma count rates are measured at the peakenergies for indium and/or vanadium as well. The off-peak measurementsare used to remove a portion of background radiation from the peakenergies. The background removal is accomplished using spectroscopysoftware routines.

Additional background radiation emanating from the presence of materialssuch as aluminum, silicon, iron, or the like, is also removed prior toobtaining the peak energies for the indium and/or vanadium that isinjected into the fracture. Materials such as aluminum, silicon, iron,or the like, are generally present in the formation and in the well-borecasing and also generate gamma radiation due to the neutron bombardment.Removal (subtraction) of this contribution to background radiation alongwith the off-peak energy radiation generally leaves the peak energies ofthe injected indium and vanadium. These peak energies can be used toestimate the geometry of the fracture. In an exemplary embodiment, thepeak energy positions of the injected indium and/or vanadium can be usedto determine the fracture height.

In one method of estimating the radiation due to materials such asaluminum, silicon, iron, or the like, the formation fracture isirradiated with neutrons during a single logging pass. During this pass,gamma ray spectroscopy of the entire spectrum of energies is performed.After the logging pass, all of the radiation due to materials having ashort half-life such as that from the vanadium and/or indium, will dieout, leaving behind radiation emanating from those elements that arenaturally present in the fractured formation.

In order to measure the fracture height in a single pass, it isdesirable to obtain gamma ray measurements that cover the entirespectrum of energies of the gamma rays emitted by the vanadium and/orthe indium as well as other materials that are naturally present in thefractured formation. The radiation measurements are made by using adetector present in the logging tool. As noted above, measurementsobtained at off-peak energies are subtracted from the measurements madeat peak energies to remove the background radiation. This backgroundradiation involves radiation signals that are obtained from theactivation of nuclei that are generally present in formations such asaluminum, silicon iron, or the like. It is to be noted that someradiation may also emanate from materials used in the well-bore casingand these are to be removed. This background radiation from materialspresent in the well-bore and formation is generated because of theexposure to neutrons in a manner similar to that coming from thevanadium and/or indium that are injected into the formation fracture.After the logging pass, the radiation emanating from the activation ofvanadium and/or indium will die out because of the short half-life ofthese materials leaving the natural background radiation from materialssuch as aluminum, silicon, iron, or the like, present in the earthformations. This background radiation can then be measured andsubtracted from the measured peak energies of the indium and/or vanadiumto estimate the fracture height.

In another embodiment, in another method of determining fracture height,tagged proppants having differing densities can be introduced into theformation. Gravitational separation of the tagged proppants can then beused to determine the fracture geometry. The heavier tagged proppantswill settle to the bottom of the fracture, while the lighter proppantswill float to the top of the fracture. In one embodiment, the proppantshaving the higher densities can be tagged with a first radiationsusceptible material, while the proppants having the lighter densitiescan be tagged with a second radiation susceptible material. Gammaradiation signals obtained from the tagged proppants can then be used todetermine the height and other geometrical features of the fracture. Forexample, if the denser proppants comprise vanadium and the lighterproppants comprise indium, then the gamma radiation signals from thevanadium and those from the indium can be used to determine the heightof the fracture.

In yet another embodiment, in another method of determining fractureheight, tagged proppants that are capable of being oriented can be usedto determine fracture height. The proppant can comprise an activematerial in addition to the radiation susceptible material, wherein theactive material can be used to orient the proppant. The active materialthat promotes orientation in the proppant can be activated by anexternal activating signal such as, for example, radio signals,electrical fields, magnetic fields, ultrasonic signals, or the like. Inone embodiment, the tagged proppant can comprise electrically conductiveparticles such as for example, conductive metal particles, carbonnanotubes, or the like, which permit the proppant to be realigned by anapplied electrical field. Thus, after the tagged proppants areintroduced into the formation, the active materials can be activated bythe application of the appropriate external activating signal to promotereorientation. After the desired orientation is achieved, the taggedproppants are bombarded with neutrons to produce gamma-rays. Themeasured gamma-rays are correlated with the orientation to deriveinformation about the fracture geometry. When tagged proppants arecapable of being oriented, the logging tool can comprise an apparatusthat is capable of orienting the suspended particles as well asmeasuring the resulting orientation in the tagged particles.

This method is advantageous since it uses a single pass of the loggingtool to determine the fracture height. After irradiation, the radiationsusceptible material can be left downhole because of its extremely shorthalf-life. This permits re-determining the fracture geometry aftersubstantial intervals of time after the fracturing has occurred. Forexample, a determination of fracture geometry can be initially made assoon as the fracturing occurs. Since the radiation susceptible materialscan be retained in the formation without any damage to the soil orunderground water or to personnel above ground, another determination offracture geometry can be made after an interval of several months toobserve changes in the fracture.

Other methods generally require two or more passes of the logging toolto determine the fracture height. The present method is alsoadvantageous in that it prevents contamination of the soil andunderground water with radioactive materials. Since the radiationsusceptible materials used in the present method have a short half-life,contamination of underground water streams and soil can be prevented. Inaddition, if flow back from the well occurs, then the risk of personnelbeing subjected to radiation is substantially reduced.

This method also avoids the use of radioactive tracers. The use ofradioactive tracers generally contaminates underground water streams andis environmentally hazardous. Other methods that use radioactive tracersmust perform a background-logging pass to remove the natural gammaradiation coining from the materials present in the formations. Thisbackground removal is most critical when either the injected radioactivematerial is dying out, and/or when this material was poorly positioned,and/or when this material was positioned deeply into the formationmaking it difficult to find.

In order to provide a better understanding of the present inventionincluding representative advantages thereof, the following examples areoffered. It is understood that the examples are for illustrativepurposes and should not be regarded as limiting the scope of theinvention to any specific materials or conditions.

EXAMPLES

A pre-cured resin coating was developed by pre-mixing a solution of 70grams of Oilwell resin 262E is a liquid phenol-formaldehyde resoleresin, and (3.75 grams of 80%) or (6.0 grams of 50%) of a Vanadium alloycompound. The pre-mixed solution was then added to 1 kilogram fracturingsubstrate pre-heated to a temperature between 380 to 400° F. (193 to204° C.). The substrate and pre-mixed solution were then mixed togetherwith constant agitation. A surfactant (Chembetaine) was added at 2minutes, 30 seconds into the cycle. Agitation was stopped at 3 minutes,40 seconds and the coated material was placed into an oven pre-heated to320° F. (160° C.) for a post bake of 3 minutes, 40 seconds. The coatedmaterial was then removed from the oven and cooled to room temperature.

Using the procedure above, a number of vanadium alloy compounds (withvarying particle sizes) were prepared for further testing. The resultsappear in Table 1.

TABLE 1 % Concentration Substrate % Loss Crush Particle of V on Mesh onResistance Vanadium Alloy Compound Size¹ Substrate² Size³ Ignition⁴ (wt% fines)⁵ 80% Ferrovanadium alloy ~40 micron 0.211 20/40 3.90 9.4 50%Aluminum vanadium alloy ~10 micron 0.305 20/40 80% Vanadiumnitride/carbide  ~3 micron 20/40 3.82 12.8 80% Vanadium nitride/carbide ~3 micron 0.255 40/70 3.73 2.3 ¹Particle size as determined by aCoulter Particle Size Analyzer ²Metals Analysis as determined by AtomicAbsorption by Acid Digestion ³Substrate Particle Mesh Size as determinedby API (American Petroleum Institute) RP-56, section 4 ⁴Loss on Ignitionwherein sample is ashed at 1700° F. (927° C.) for 2 hours and weightloss recorded ⁵Crush Resistance as determined by API RP-56, section 8:

While the invention has been described with reference to exemplaryembodiments, it will be understood by those skilled in the art thatvarious changes may be made and equivalents may be substituted forelements thereof without departing from the scope of the invention. Inaddition, many modifications may be made to adapt a particular situationor material to the teachings of the invention without departing from theessential scope thereof. Therefore, it is intended that the inventionnot be limited to the particular embodiment disclosed as the best modecontemplated for carrying out this invention, but that the inventionwill include all embodiments falling within the scope of the appendedclaims.

1. A proppant, comprising: a substrate; and a coating disposed upon thesubstrate, wherein the substrate or the coating comprises: a firstradiation susceptible material selected from the group consisting ofcomprising indium, vanadium, and combinations thereof, and a secondradiation susceptible material selected from the group consisting ofiridium 191, iridium 193, cadmium 113, dysprosium, europium, lutetium,manganese, gold, holmium, rhenium, samarium, tungsten, and combinationsthereof, wherein the first radiation susceptible material and the secondradiation susceptible material are non-radioactive until bombarded byneutrons.
 2. The proppant of claim 1, wherein the first radiationsusceptible material comprises vanadium and wherein, after beingirradiated, the first radiation susceptible material has a half-life ofabout 10 seconds to about 50 minutes.
 3. The proppant of claim 1,wherein the proppant comprises 0.01 wt % to about 35 wt % weight percentof the combined first radiation susceptible material and the secondradiation susceptible material.
 4. The proppant of claim 1, wherein thesubstrate comprises an organic particle having a filler dispersedtherein; and wherein the first radiation susceptible material, thesecond radiation susceptible material, or both are dispersed within thesubstrate.
 5. The proppant of claim 1, wherein the first radiationsusceptible material is selected from the group consisting of vanadiummetal, a ferrovanadium alloy, an aluminum vanadium alloy, a vanadiumnitride carbide and combinations thereof.
 6. The proppant of claim 1,wherein the first radiation susceptible material comprises a vanadiumnitride carbon powder.
 7. The proppant of claim 6, wherein the vanadiumcarbon nitride powder has a particle size of about 1-15 microns andwherein the amount of vanadium carbon nitride powder comprises 0.01 to 5wt % as vanadium metal, based on the total weight of the proppant. 8.The proppant of claim 1, wherein the coating comprises an organiccoating, an inorganic coating, or a combination thereof.
 9. The proppantof claim 8, wherein the coating comprises a polymerized epoxy, apolyacrylate, a polymethacrylate, a polymerized phenol-formaldehyde, apolymerized epoxy-modified novolac, a polymerized furan, a polymerizedurea-aldehyde, a polymerized melamine-aldehyde, a polyester, apolyalkyd, a polymerized phenol formaldehyde novolac, a polymerizedphenol formaldehyde resole, a polymerized phenol-aldehyde, a polymerizedresole, a polymerized novolac, a polymerized epoxy modified phenolic, apolymerized urethane resin, polysiloxanes, or a combination comprisingat least one of the foregoing.
 10. The proppant of claim 1, wherein thefirst radiation susceptible material comprises a vanadium materialselected from the group consisting of vanadium metal, a vanadium alloy,a vanadium salt, a vanadium composite, a vanadium suspension, andcombinations thereof.
 11. The proppant of claim 1, wherein the firstradiation susceptible material comprises a vanadium material selectedfrom the group consisting of vanadyl sulfate, vanadyl sodium, vanadylpotassium orthovanadate, sodium metavanadate, potassium metavanadate,chloride salts of vanadium, vanadium trioxide, vanadium pentoxide, andcombinations thereof.
 12. The proppant of claim 1, wherein the firstradiation susceptible material is a vanadium material comprising from0.01 to 5 wt % based on the total weight of the proppant.
 13. Afracturing fluid comprising the proppant of claim
 1. 14. A composition,comprising: a fracturing fluid; and a proppant disposed in thefracturing fluid, wherein the proppant comprises: a substrate and acoating disposed upon the substrate, wherein the substrate or thecoating comprises: at least a first radiation susceptible materialselected from the group consisting of comprising indium, vanadium, andcombinations thereof, wherein the radiation susceptible material isnon-radioactive until bombarded by neutrons
 15. The composition of claim14, wherein the proppant further comprises a second radiationsusceptible material selected from the group consisting of iridium 191,iridium 193, cadmium 113, dysprosium, europium, lutetium, manganese,gold, holmium, rhenium, samarium, tungsten, and combinations thereof,wherein the second radiation susceptible material is non-radioactiveuntil bombarded by neutrons
 16. The composition of claim 15, wherein theproppant comprises 0.01 wt % to about 35 wt % weight percent of thecombined first radiation susceptible material and the second radiationsusceptible material.